The present invention relates to a magnetic head supporting device, and more particularly to a magnetic head supporting device used in a magnetic disk apparatus.
In general, a magnetic disk apparatus (hard disk drive) comprises a support spring (hereinafter referred to as "suspension") for supporting a magnetic head slider (hereinafter simply referred to as "slider") carrying a recording/reproducing element (magnetic head), a magnetic head supporting device having an actuator for moving the support spring in a radial direction, and a magnetic disk medium (hereinafter simply referred to as "medium") for magnetically accumulating information.
The suspension takes an important role for maintaining a followability of a slider to the medium in an air floating state caused by the rotation of the medium and in a seeking operation. The seeking direction changes in accordance with a kind of actuators. A linear actuator moves the slider in parallel with the radial direction of the medium. Also, a rotary actuator moves the slider substantially in the radial direction of the medium about a rotary center axis of the actuator.
FIG. 8 shows the prior art. The piece of prior art shown in FIG. 8 is disclosed in FIG. 4 of Japanese Patent Application Laid-Open No. Hei 1-062877. The prior art system shown in FIG. 8 is provided with a suspension 54 having elongated holes 56 and 57 (formed into an inverted V-shape to be directed to a center of rotation) which holes are not in parallel with a seeking trace direction A (seeking direction). The suspension 54 is held by a linear actuator 52 through a magnetic head arm 53. Also, a slider 55 moves in the radial direction above a magnetic disk 100.
With respect to the suspension 54 of these components, the above-described Japanese Patent Application Laid-Open No. Hei 1-062877 discloses a technique for reducing an amplitude of a primary bending vibration with a structure where the grooves that are not in parallel with the longitudinal direction (i.e., corresponding to the seeking direction in this case) are formed in the interior of the suspension 54.
On the other hand, Japanese Patent Application Laid-Open No. Hei 5-303730 discloses a technique for moderating a rigidity by providing a narrowed portion in the suspension and at the same time enhancing a followability in a slight floating state by miniaturizing the slider portion.
However, when the slider is moved in the seeking direction by the actuator, there is a problem in which the suspension is flexed or a distance between the slider and the medium is varied so that it would be difficult to exactly position the track in place. Then, in some cases, since the slider is brought into contact with the medium due to the flexure of the suspension, there is a fear that a recording/reproducing error occurs or the medium is abraded due to the contact of the recording/reproducing element, resulting in cancellation of the record.
In this case, the larger the rigidity in the seeking direction, the smaller the flexure in the seeking direction of the suspension will become. In particular, as the force of the suspension toward the surface of the medium, i.e., the load is smaller, and the thickness of the spring should be smaller. Accordingly, in such a case, the rigidity becomes low.
In this case, in order to reduce the load without changing the thickness of the spring, it would be sufficient to form grooves or holes in the suspension. However, the above-described elongated holes 56 and 57 shown in FIG. 8 (Japanese Patent Application Laid-Open No. Hei 1-062877) are not in parallel with the seeking direction. For this reason, as a matter of fact, it is difficult to increase the rigidity in the seeking direction (formed into an inverted V-shape to be directed to the direction of the magnetic disk).
In view of the above-noted difficulties, the present inventor has experimentally found that the direction of formation of the elongated holes formed in the suspension has something to do with the rigidity of the suspension.
On the other hand, the "narrowed portion" at the tip end of the suspension disclosed in Japanese Patent Application Laid-Open No. Hei 5-303730 reduces the rigidity in the seeking direction.
Furthermore, in comparison with the above-described air floating type slider (hereinafter simply referred to as "floating type slider"), a contact type slider disclosed in Japanese Patent Application Laid-Open No. Hei 6-162445 is highly likely to be affected particularly by a difference in rigidity in the seeking direction since it is brought into direct contact with the medium to generate larger frictional forces. In other words, the rigidity in the seeking direction brings about the more strain (i.e., the flexure of the suspension).